In the spotlight: Can lights be used to mitigate fox predation on a free-range piggery?

Abstract

Across the world, the impact of livestock predation is a significant economic and welfare issue for producers, particularly for free-range farms. Non-lethal predator control methods have broad consumer appeal, but in most instances there has been little validation of their effectiveness. Predation remains a major limitation for outdoor piggeries, where predation is both an economic and welfare problem. We compared the efficacy of (1) no lighting (un-lit control), (2) commercially-available Foxlights®, and (3) motion-activated spotlights to test whether lights can deter red foxes (Vulpes vulpes) from approaching farrowing huts on an outdoor piggery breeding facility. Passive infrared camera traps were mounted at the entrance to the farrowing huts to monitor fox activity over 85 farrowings. Multiple incidences of foxes carrying piglets away from the huts (both dead and alive) were recorded. There were significant lighting treatment effects on fox activity (P = 0.031) and farm records for number of piglet births recorded per sow (P = 0.015). Compared with the un-lit control treatment, farrowing huts in the Foxlights® treatment had 12 % more fox activity, and 23 % fewer piglet births recorded for sows in these paddocks. Controlling for environmental covariates, there was predicted to be 39 % more fox activity on dark (new moon) nights for the Foxlights® treatment. By contrast, compared with the control, farrowing huts in the motion-activated spotlight treatment had similar overall fox activity (–5%) and piglet births recorded (–3 %). Interactions with moon phase (and rainfall as a prediction of cloud cover) are likely to be important considerations for studies of lighting deterrents, and we found that weaning rate (farm records for the proportion of piglets born alive that survived to weaning) was only influenced by lunar illumination (p = 0.003), with 16 % fewer piglets born around bright (full moon) nights surviving to weaning compared with dark (new moon) nights. Rather than being a deterrent, Foxlights® appear to be an attractant to foxes on this property, where there was no reinforcement with aversive human activity or other deterrent modalities. The motion-activated spotlights may be more effective because they are only activated when an animal is present and should therefore have reduced likelihood of habituation; however we found no data suggesting that they improved the outcome over our un-lit control treatment for this outdoor piggery.